Date   

Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

Tyler Bowman - Explore Scientific Customer Service <Tbowman@...>
 

Hey if you could send me a email at tyler@... we can figure out whats going on.


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

 

Joseph,
 
Re: The Clutch...
If you scroll down the stardeck observatory link, you'll see some rather decent exploded photos of an LXD75, our EXOS2's progenitor.  Our mounts have bearings on all axes and the bushings/spacers are a bit different, but the general arrangement of things is much the same. 
If you scroll to the RA assembly diagram, to the right is a dotted circle that encloses the "axis rotation lock assembly" (aka clutch, brake, etc.).  A lever, a screw, and a little dot of something, which is effectively a small brake shoe.  I've attached a photo of mine, taken when I had my mount apart.  Turn the lever and the brake shoe presses on the ring/drum gear's side.  This mechanically links the ring gear to the outer shell of a given axis, so the motor can rotate it for tracking and slewing.  Disengage the clutch and the axis is free to rotate for balancing.



There's not much to go wrong with it, or to adjust.  I believe that the screw in the lever can give you a bit of control over tension, but that's about it.  

Re: wiggling...
The ring gear is driven by a worm gear.  Worms drive, they aren't driven, so you won't see your motor pulley wiggle.  If the axis is moving, the usual cause is just normal backlash that you just have to manage around.  But there is one other possibility, and this might cause trailing. Take a look at Section 7.3 in the tuning doc I linked.  That deals with adjusting the tension on the worm gear shaft.  They are sometimes mis-tensioned, either too tight or too loose.  If too loose, the worm could shift along its length as rotational force on/from the axis varied.  While the worm will refuse to be driven, I suppose it's possible that it might shift.  Easy enough to check, but you'll need to pop the covers to do that.  
 
Hope this helps!
--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: IEXOS-100 can't get round stars due to RA erros? #iEXOS-100

NewAP
 

Hi Brian, thanks for the input, I thought about it a bit, the focusing was not perfect but it always showed up along RA direction, so I suspect the RA movement has some impact, and it is true we can't rule out the possibility of lens or focusing.

Yi  

On Fri, Jan 8, 2021 at 10:02 AM brian skinner <brianjimskinner@...> wrote:
Hi there, I may be wrong here of course but it looks to me that your problem could be bad focusing??
--
Brian Skinner
iEXOS100
Canon 1300d dslr
Various lenses
ES Polar scope
Sequator image stacker
PIXR image editor


Re: IEXOS-100 can't get round stars due to RA erros? #iEXOS-100

brian skinner
 

Hi there, I may be wrong here of course but it looks to me that your problem could be bad focusing??
--
Brian Skinner
iEXOS100
Canon 1300d dslr
Various lenses
ES Polar scope
Sequator image stacker
PIXR image editor


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

nickerson.joseph@...
 

Robert I appreciate your help. I understand the concept of backlash. In the aircraft maintenance world we always called it play. Tomato, Tomato. I have been up and down my image train a half dozen times looking for unwanted motion and could find none. And it seems the issue is worsening over time and I can say with 90% assurance that backlash wasn't always there. I opened up the side panel for the RA to inspect the gears and saw nothing askew and when I wiggled the scope again on the RA, the gears did not move. Wouldn't the gears move if the play was indeed backlash. My gut/maintenance intuition is telling me that there is something wrong with the Clutch allowing the play which turns into a slight vibration that effect the image during a hard motor push, which is why not all my subs are bad, but enough to warrant mega frustration. I don't seem to have any issues with star trails along the DEC and that sucker is solid with zero wiggle/jiggle/backlash/play. In aircraft maintenance that is called check the other side to see if it's doing it, if its not then that is most likely the issue.  Also, does anyone know why Explore Scientific isn't answering their phone.... 


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

 

Joseph,

Play (backlash...) in the gears?  Some is indeed normal.

Gears, shafts, bearings...all have tolerances.
And the spacing between the ring and worm?  It's fixed.  No play in that. 
So the best you can do is adjust the two gears to be as close as possible without actually binding. 
And where the spacing opens up...you get play/backlash.  You counteract that by managing balance.

I'm looking at your setup picture, and I see a very long focuser tube with a (heavy) filter wheel and camera at the end of it.  Is there unwanted motion there, at the sensor end?  No idea, but given your problem description, I'd be taking a close look.  Remember, you're looking for microns...

Again, FWIW.  Hope this helps...



On Thu, Jan 7, 2021, at 17:09, nickerson.joseph@... wrote:

[Edited Message Follows]

The same issue was accuring with my guide scope mounted on center line, see attached picture. I am having a hard time rapping my head around any play in the mount with clutches locked down being normal.

Attachments:
  • 20210101_112422.jpg


--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

nickerson.joseph@...
 
Edited

The same issue was accuring with my guide scope mounted on center line, see attached picture. I am having a hard time rapping my head around any play in the mount with clutches locked down being normal.


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

Walter Vinci
 

Hi Joseph,

I am totally new to the hobby too (hi everyone :)! ), actually just a couple of nights out with autoguiding, but my ES PMC-8 EXOS2 has a similar (even wider I would say) play on RA and I have no such problem (doing about 2” RMS but with round stars). 

On Jan 7, 2021, at 2:56 PM, Robert Hoskin <devonshire@...> wrote:

Joseph,

This hobby is an endless source of problem-solving opportunities  :-)

Just tossing some things out as grist for your mill...

If you tell me that your mount axes wiggle, well, you may need some mechanical adjustment (see link below).  
BUT... some play in the ring/worm gear connection is entirely normal, so while it's good to keep a mount well-adjusted, there are limits to the mechanical perfection we can achieve. 

Having said that... if you tell me that your guiding looks good, but your stars trail anyway, then I'd wonder about the dreaded "differential flexure". 
Basically, guiding well requires that the two optical trains (guiding and imaging) be absolutely rigid relative to each other. 
Relative movement of scopes in rings, focuser rotators, cameras in focusers, etc... all bad.   
I would guess that if guiding looks good, there may be motion in your imaging train.  On my scope, it was a focuser rotator.  Very convenient for visual use, but its inherent play was a bad idea for my imaging.  I locked its little grub screws down with extreme prejudice and saved the day!  

FWIW...

https://espmc-eight.groups.io/g/MAIN/files/User%20Contributions/EXOS2PMC8_TuningNotes_v2.pdf

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

 

Joseph,

This hobby is an endless source of problem-solving opportunities  :-)

Just tossing some things out as grist for your mill...

If you tell me that your mount axes wiggle, well, you may need some mechanical adjustment (see link below).  
BUT... some play in the ring/worm gear connection is entirely normal, so while it's good to keep a mount well-adjusted, there are limits to the mechanical perfection we can achieve. 

Having said that... if you tell me that your guiding looks good, but your stars trail anyway, then I'd wonder about the dreaded "differential flexure". 
Basically, guiding well requires that the two optical trains (guiding and imaging) be absolutely rigid relative to each other. 
Relative movement of scopes in rings, focuser rotators, cameras in focusers, etc... all bad.   
I would guess that if guiding looks good, there may be motion in your imaging train.  On my scope, it was a focuser rotator.  Very convenient for visual use, but its inherent play was a bad idea for my imaging.  I locked its little grub screws down with extreme prejudice and saved the day!  

FWIW...

https://espmc-eight.groups.io/g/MAIN/files/User%20Contributions/EXOS2PMC8_TuningNotes_v2.pdf

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2 290M
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

nickerson.joseph@...
 

Are you saying it's suppose to wiggle like that? 


Re: #EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

NewAP
 

I have similar issue with IEXOS-100, there might be several reasons I suspect:
First is the periodic error due to the imperfection of the gears, it causes the rocking along RA.
secondly seems the tracking rate is slightly off but I guess it will take some effort to change it, but you can try tweak it a bit by setting the custom sidereal rate, +-2 to start with.

Best,
Yi 
--
Canon 6D, Sigma 150-600mm, IEXOS-100


IEXOS-100 can't get round stars due to RA erros? #iEXOS-100

NewAP
 

Have IEXOS-100 for over a year, used for unguided imaging, and noticed that I could not get round stars, it was always elongated along RA.
Thought moving to guided imaging will resolve this issue so did the move recently, still can't fix egg shaped stars.

Imaged with Canon 6D at 300mm, 600mm over 30 sec, 60 sec. Tried to tweak the pulse rate from 0.4 to 0.5 and 0.6 without any major improvements.
Still get elongated stars, for bright stars the trails are so obvious.

I removed the motor covers and noticed that the DEC pulley seems to be more smooth than the RA pulley, which is definitely not acentric so well, but not sure if that could be the cause.

PHD2 reported RA peak-peak 30-50 seems to be OK. RA RMS errors seem to be reasonable as well (1.x arcsec/s), but the drift limited exposure was very low in the 0.3-0.7 second range.
PHD2 logs have been uploaded, so are some sample pictures.

Please help and suggest. Quite confused and thought maybe I am unlucky the unit has problems with RA tracking?

NY
--
Canon 6D, Sigma 150-600mm, IEXOS-100


#EXOS2 My RA on my mount is wiggling, Causing Star Trailing!!! #EXOS2

nickerson.joseph@...
 
Edited

HELP!!! I have been using the EXOS2-GT w/PMC8 for about 6 months and have been mostly happy with the purchase. Most my frustrations stemming from just being new to the hobby. I use my mount for astrophotography only and noticed over the last month I was losing more and more subs to the same issue of  very slight star trail. My last few sessions though I am now losing over 50% of my subs regardless of exposure time. My polar alignment is spot on using shape cap, my guiding stays under .20 on RA and DEC. Today as I was making sure all my equipment was secure when I noticed that there is "play" on the mounts RA, no matter how much a crank the clutch, I still get movement, with or without power on the mount, Parked or Un-parked. My DEC is solid as a rock. I can only assume this is my issue. I have been calling Explore Scientific all day today but no one is answering. I am not sure where to go from here...Any assistance would be greatly appreciated. I have attached a sub of the star trail and a video of the play. Sincerely.....


Re: Connection Issue #EXOS2 #pmc-eight

Al Parise
 

lol

yea the 12v power brick that came with the mount
somewhere on the line closer to the brick is a weak spot
when i fiddle with it the power flashes on/off
so the unit must not have been getting full power, thus the 2 lights flashing

I found another power brick, off a portable hd case,  with same output and pin size
and it works, full power

going to order a new cord


Re: Connection Issue #EXOS2 #pmc-eight

Wes Mcdonald
 

You know al I almost asked if you had the pmc8 turned on😂 but didn’t.  It’s an old joke about computer phone support. “ well sir before we begin let me just ask you if you have plugged in and turned on your computer”🤬😅

Anyhow that’s great.  What power cord are you taking about, the 12v power line brick or another thing you made?

Wes

--
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired


Re: Connection Issue #EXOS2 #pmc-eight

Al Parise
 

Hi Wes
problem solved
was the power cord
found another cord and all works now
5       Received: ESGp0000000!
4       ComManager:     Serial Returned: ESGp0000000!
3       ComManager:     Start Sending Serial Message: ESGp0!
2       Sending via Serial: ESGp0!

the lights that were flashing are now solid
plus now 2 different lights doing their thing

so if these lights are flashing and no other lights (serial on left)
led 6 power red - top left
and led 2 wifi green - mid bottom
then its the power cord
should add this to the trouble shooter or knowledge base

Wes thanks for your time
really appreciated

regards
Al


Re: Connection Issue #EXOS2 #pmc-eight

Al Parise
 

Hi Wes
I may have found the issue
I been moving the box around and took it to my desktop pc
installed all software and drivers and it would not connect
moved it back to my laptop and noticed while plugging in power
there was no power to box
ran cord thru my fingers then came to  a spot in the cord  then the box lit up
lol
yes positive, no pmc8 wifi network
with serial port on left
these lights on the pmc8 box are flashing, no other lights doing anything
led 6 power red - top left
and led 2 wifi green - mid bottom

looking for another cord
maybe not enough power thru cord, so lights flashing ?
what a pita
will advise
regards


Re: Connection Issue #EXOS2 #pmc-eight

Wes Mcdonald
 

Al:

The PMC8 network needs to appear in the WiFi network connections...are you sure it is not?  This does not sound good.

AS you view PMC8 front panel with serial port on left, tell me again what flights you see and what they are doing?

Wes.


--
Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired


Re: Connection Issue #EXOS2 #pmc-eight

Al Parise
 

Hi Wes
ok
win device manager - usb serial com port 7, driver looks good, no complaints
got new ftdi cable installed, all good, removed old/hidden coms

Ascom Driver - serial, port 7

CM -  connection - exos2, com port it shows port 7, pressing find  it says -
does not automatically find the com port to pmc8, make sure it is connected
pressing the do it button says it appears scope is not connected

no pmc8 wifi network appears in network, so stuck in serial

CM-Advanced - serial on, sending ESGV! , with extensive debug  returns this
77       Received: 
76       ComManager:     Serial Returned: 
75       ComManager:     Start Sending Serial Message: ESGp0!
74       Sending via Serial: ESGp0!

parallax - port 7, it sees the port, baud 115200, enable - seems to connect to port
not sure I know what im doing with this but entering in command ESGp0! or ESGv! returns no result

regards
 


Re: Connection Issue #EXOS2 #pmc-eight

Al Parise
 

Wes
I have read a lot of your posts here and have learned a lot from them

thank you so much for the quick reply

will go thru your suggestions and report back
regards

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